1. Field of the Invention
Embodiments of the present invention generally relate to the field of nuclear magnetic resonance and, more specifically, to the body/head coil switching in nuclear magnetic resonance.
2. Description of the Prior Art
Currently, nuclear magnetic resonance technologies find wide application in the medical arts. Magnetic Resonance Imaging (MRI), also referred to as Nuclear Magnetic Resonance Imaging (NMRI), is a diagnosis method that generates an image with the use of resonance of atomic nucleuses in a magnetic field. Its basic principle is that an image is constituted by using inherent characteristics of atomic nucleuses and interaction of magnetic fields. A class of atomic nucleuses that are closely related to body tissues will generate a magnetic resonance signal under the action of an external radio frequency (RF) field, and a set of parameters related to the magnetic resonance may be used as variables for imaging.
A RF coil is an important part of a MRI system, and all of magnetic resonance scans and examinations will be done with the use of the coil. Its function is to transmit RF pulses and receive MRI signals, and is an important link in MRI system imaging. A RF coil may be classified into a head coil, a body coil, and the like, depending on its structure and the purpose of the examination. In practice, depending on the part to be examined, the size of lesion and the purpose of the examination, switching is required among different RF coils, thereby improving the image quality of the MRI examination, improving the diagnostic coincidence rate of the MRI examination, and enlarging the application range of the MRI examination.
In a magnetic resonance imaging apparatus, a power amplifier (PA) is one of its important components. A PA consumes power of a power supply, and outputs RF power. RF PA will output different power levels when it is connected with a body coil and a head coil, respectively. For existing MR PA designs, there are two methods to implement this. The first PA design is to use a six-way parallel connection to meet the requirement of a body coil, and switch to a head coil when it is connected with some other coils. However, a disadvantage with this method is that the efficiency is low when it is connected with a head coil. The second PA design is to use a sicx-channel parallel connection to meet the requirement of a body coil, and design another separate channel for connecting to a head coil. However, a disadvantage with this method is that it is expensive.
Therefore, there is a need for a novel PA design that can improve the efficiency while reducing the cost.